1. Field of the Invention
This invention relates to an air conditioning and dehumidification system. More particularly, it refers to a closed loop, single pipe, reverse fluid flow air conditioning and dehumidification system serving multiple enclosures.
2. Description of the Prior Art
In a hydronic system for cooling and dehumidifying a building, or a group of buildings, employing a single pipe supply arrangement, a progressive temperature change occurs to the entering water temperature (hereafter EWT) of subsequent loads connected along the single pipe circuit. Heretofore, this EWT change was avoided by adding a reverse return piping system. All load circuits are piped in parallel so that the flow of the first load fed will be the last flow returned to the chiller. In another two pipe direct return system, the first load fed is the first load returned. Each load circuit of either arrangement has to be balanced. Failure to establish the required balance causes low system temperature differences, high pump horsepower and inefficient chiller operations. Both forms of two pipe systems are labor intensive to design, install and commission.
In addition to the limitations discussed above, present day systems use two way control valves applied to each coil. This throttling of coil flow duplicates the same variable flow effect of three way valves. The high head loss creates a variable volume system. Variable speed system pumps are applied to reduce operating costs. Pump speed is adjusted to suit worst load conditions. All other loads continue to pay energy penalties.
Examples of pumps and zoning circular controllers used in prior art cooling system are described in U.S. Pat. Nos. 5,466,995 and 5,664,939, both incorporated herein by reference.